Rex (レックス, Rex) is the main protagonist of Xenoblade Chronicles 2.
Rex was a 15 year old salvager from Letheria who lived on a titan named Azurda or "Gramps" until a fated meeting with the Aegis Pyra while on a salvaging mission with Jin, Malos, Nia, and Dromarch, but after touching Pyra's sword, Jin kills Rex by impaling him in the heart, and reveals that he leads an organization known as Torna. Rex wakes up in a memory of Elysium and meets Pyra who requests him to take her to the real Elysium in exchange for bringing him back to life. Immediately after being revived, Rex and Malos, Torna's second-in-command as well as another Aegis, battled each other until Azurda rescues Rex and Pyra, as well as Nia and Dromarch who were initially members of Torna but defects to Rex's side. After that, they begin to travel around Alrest starting at Gormott, meeting Tora, Poppi, Mòrag, Brighid, Vandham, Roc, Zeke, and Pandoria, on their journey to reach Elysium while having run-ins with three more Torna members; Akhos, Patroka, and Mikhail.
As a costume
Rex was considered for the roster alongside other prospective characters like ARMS's Spring Man and Pokémon's Decidueye, however he could not be added due to Xenoblade Chronicles 2 being announced after character planning finished in 2016 (Byleth’s inclusion as DLC likely indicates this was only the case for the base game). As an offered alternative, Rex appears as a costume for the Mii Swordfighter. Azurda (otherwise known as Gramps) in his miniature companion form appears in the set's helmet. The costume comes as a free bonus with purchase of the Fighters Pass Vol. 1. Rex also appears as a Primary Spirit.